(a) Field of the Invention
The present invention relates to a film sheet and a greenhouse provided with the same, and more specifically, to a film sheet for area-focusing of sunlight and a greenhouse provided with the same.
(b) Description of the Related Art
Recently, research and development on clean and renewable energy has been actively conducted due to depletion and increasing price of the natural resources such as fossil fuel and oil etc. Examples of the clean and renewable energy include a solar energy, wind energy, tidal energy, and so on. Particularly, a research and development on effectively using solar energy to conserve natural resources has been actively conducted.
It is important to increase the efficiency of focusing sunlight in order to effectively use the solar energy. Therefore, a Fresnel lens, which can raise the efficiency of focusing sunlight, has been developed and used. The Fresnel lens is manufactured to have a single focus for point-focusing light. In this case, intensity of the beam has a Gaussian distribution. That is, intensity of the beam is greatest at the center at which the focus is located and the intensity of the beam becomes weaker going to an edge thereof.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.